1. Field of the Invention
The present invention relates to an apparatus for enhancing the performance of a heat pump and the like, and more particularly to such an apparatus that is relatively inexpensive to construct and maintain, and which is economical to operate, the apparatus increasing the operating efficiency of the heat pump over a wider range of environmental ambient temperature conditions.
2. Description of the Prior Art
Heat pumps in various configurations, capacities, and other operational characteristics have been known and utilized for many years. It is well known that a heat pump operates by raising the temperature level of heat by means of work input. In its most common configuration, a compressor takes refrigerant vapor from a low pressure, low temperature evaporator and delivers it at high pressure and temperature to a condenser. As a general matter, the pump cycle is identical with that of the customary vapor-compression refrigeration system.
Recently, heat pumps have found increasing acceptance when operated in combination with solar heating systems. This union of solar heating systems and heat pumps is attractive because the efficiency of a solar collector rises rapidly with lower collection temperatures such that an electrically driven heat pump can utilize the solar heat source with a resulting higher overall coefficient of performance.
It should be understood, however, that heat pumps, in and of themselves, have not come into wide usage for the comfort heating or cooling of living spaces because their effectiveness over a range of outside ambient temperatures is quite limited. As a general matter, it is well understood that the heat which can be delivered by a heat pump decreases significantly as the outside ambient temperature descends below 36.degree. Fahrenheit and becomes zero when the outside temperature reaches approximately 28.degree. Fahrenheit. Moreover, it is well known that when the outside ambient temperature rises above 78.degree. Fahrenheit there is the presence of excess heat which correspondingly decreases the cooling capacity of the heat pump. As should be understood, sundry devices and systems are offered to correct this situation such as storage systems, supplementary heaters and compressors operating alternatively in series or in parallel.
The prior art apparatuses which have been designed to address the problem of the limited temperature range and effectiveness of a heat pump have met with varying degrees of success, but they have also suffered from numerous shortcomings. One of the major shortcomings is that the cost of operating these numerous supplementary devices is substantial. Moreover, it is frequently the case that these supplementary devices are in themselves expensive, and therefore cost prohibitive. As a consequence, heat pumps have not been used extensively for comfort control in homes, business or the like.
Still another significant problem with the prior art devices is that they are not as versatile as desired in many operational environments and are not as readily adaptable to onsite conditions, as is normally encountered. It should be understood that the various manufacturers of heat pumps have developed sundry different designs and configurations and therefore supplementary devices are often difficult to install and thereafter operate. This problem can be particularly acute in residential installations where only limited space is available.
Similarly, the prior art supplementary devices once installed are difficult to remove or disassemble for maintenance and the like.
Therefore, it has long been known that it would be desirable to have an apparatus for enhancing the performance of a heat pump and the like which is adapted for installation on a wide variety of different models of heat pumps and which can, in some instances, be adapted on-site during such installation; and which operates cooperatively with the heat pump to achieve increased heat pump efficiency over a wider range of outside ambient air temperatures; which is readily removable for maintenance after installation; and which can be manufactured, installed and operated at a relatively nominal price.